Milling machine for milling slots by slabbing cutters or end mills



0. FORST April 14, 1931.

MILLING MACHINE FOR MILLING SLOTS BY SLABBING CUTTERS 0R MILLS FiledFeb. 15, 1928 2 Sheets-Sheet l t s w ,mffm w 3 a w i J a April 14, 1931.FQRST 1,800,991

MILLING MACHINE FOR MILLING SLOTS BY SLJABBING CUTTERS 0R END MILLSFiled Feb. 15, 1928 2 Sheets-Sheet 2 Z5 Jnvem/or' 2/ 20 Osgalal 751's?Patented Apr. 14, 1931 umrao TE PATENT oFFlica oswannrons'r. or sounder,GERMANY lemme manner." For: mums SLOTS BY sLABBmG warms or. mansapplication nrerrebmar 15, 1928, Serial 1%. 254,360; and in GermanFebruary 22. 192?.

My invention relates to milling machines and more particularly tomachines for nulling slots by slaibbing cutters or end mills.

It is an object of my invention to reduce transverse forces the powerinput for feeding, to prevent" creeping of the cutters antl tofacilitate: the removal of the chips.

To this end, in addition tothe rotation andthe feed imparted to thecutter I impart 1Q reciprocation to it at right angles to its feedingmovementa ndtransversely to its axis of V I may employ slabbing cutterssupportedat both ends for milling slots, or end mills I supported atoneand only for milling. splines eta, orderto mill slots 'etc by feedingthe milling" cutters transversely totheir axis, as for splining shafts:

This operaii' on as pevfiormed heretofore inavolves cutting on half theperimeter of the cutter; it e. on that half thereof which lies in thedirection of feed of the cutter; and this not only increases thetransverse forces but st'flch thirdmovement being'transverse to both thedirection of feed and the axis of the cutter so that the cutter iscaused to out at most only on a quarter ofits perimeter at any instant,the active cutting snrfhcebecoming a maximum at both ends of. thetransverse reaffirmation of the: cutter, while during. suchreciprocation the active cutting. surface ex. tends over only acomparatively small portion of the perimeter-of the cutter, the lengthofthis portion being a function of the chip thickness and of; theperimeter of the cutter. litis another object of my invention to providemeans for making. up for the reduction 50 on the diameter of the cuttersdueto; wear and regrinding, and to this end I make the stroke of thereciprocation variable.

R'eciprocation may bereflfected by any suitable means. I prefer crankdrives they operate: without jerks; but cam drives and other mechanismsmay alsobeprlovided'.

In the accompanylng drawings, several embodiments of my invention areillustrated diagrammatically by way ofexample Fig.1 1 is an elevation.of at complete ma chin Fig. 2is a sectionon the line II-]II in Fig. 1,drawngto a larger scale,

Fig; 3- is a section on the line III-11 in Fig. 2,

Fig. 4- is: a" detail, U i

Fig. 4m isa diagrammatic viewillustrating the operation of theacuttergFigs. 5 and 6' illustrateitwo modifications of the mechanism for.imparting: reciprocation to; the cutter, and. e

i Fig. 'Fis a section on a large scale showing means for varying. thestroke of. the reciprocation. i

Referring now to the drawings; and first to Figst 1 to 43.1 is theframeof a millin machine; 2 isarocking arm, and 3' is a hollorw shaft aboutwhich thearm is rocked. onv the framel. The manner in whichthe reckingarm; Qis carried on the frame isnot described in detail as it forms nopart of the present. inventions 4 is a sleeve inserted in the freeend ofthe arm- 2",- 5 is a chuckat the end of the sleeve for holding thecutter, 6- is a guide bush arranged in line with the chuck or cutterholder" and positioned at theend of a bracket 7 and 2" is an extensionprojecting upwardly from the free end of the armLEZ andserving as guidefor the bracket 7. The cutter is thusprovided' with two pointsofsupportis e. the holder 5 and the bracket 7.

As mentioned, may employ any type ofmilling; cutters, fragile cuttersbeing. supported by the bush in the bracket 7 at their free end, and endmills being chucked at one end. I may also provide combined milling.oattersand drills, by which first. a holeis drilled. in. el shaft'orother part, and theho-le '0 is then extended or enlarged into a slot orV ley 10 through the medium of a belt, whereby a hollow shaft 11integral with or conpulleys are mounted, is rotated. V

12 is a crank, which is carried in suitable hearings in the frame 1(Fig.3), 13"is its pin, 14 is-.a link onthe pin, 15 is a doublearmedlever fulcrumed at 16 to which the link 14Lis connected at one end, 17is a' link at the other end of the lever 15,18 is a pin at the end ofthe link, and'19 is abracket in which the pin- 18 is secured and whichis attached to the rocking arm 2. The radius of the crank 12 may bevaried by any suitable means, .not shown; f

Referring now to themodification shown in Fig. 5,. there is shown aneccentric for reciprocating the chuck or holder," sucheccentricreplacing the rocking arm 2 shown in Fig. 3. 12 is a crank,'and 20 is alink. on the nected to the holder, and upon which the pin of the crank.The link20 is pivotallyconnected with anarm 21' filed to a shaft 22which is mounted to rock about an axis 23, and 24 is an arboursupporting the chuck or holder 5. The-axis 25 of the arbour 24 isarranged eccentrically with respect to the axis tion of the crank12'causes reciprocation of theslide 29.

Means for varying the pitch of the axes 23 and 25 may comprise a sleeve26 (Fig. 7) which isinserted between" the shaft 22 and the arbour 24 ineccentric position, 27 is the axis of the sleeve 26. With the eccen- 26,from zero to the maximum 23, 25, shown in Fig. 7, "as both eccentricsare added in the illustrated position of the parts. 7

The peculiar novel operation of my cutter will be understood best byreference to the diagrammatic view, Fig. 4a, in'which C'desi'gnates thecutter and B a blank in which 'a slot 'is to be produced by said cutter.In addition to rotating about its'own (longitudinal) axis, the cutter Ghas a feeding movement,

V lines F and G, as indicated atiJ.. v tries. 23, 27 and'25, 27 equal,it ispossible to vary the eccentricity by turning the sleeve beginningof the machining, the bank is bored or drilled to produce therein a holeD of suflicient size to receive the cutter C. If the cutter had only thetwo movements referred to above, it would produce in the blank a slot orgroove of uniform width at its central portion, but, having enlargedrounded ends, as indicated by dotted lines; that is to say, the upperboundary of said slot or groove would be the upper horizontal line E,while its-lower boundary would be the dotted line.F,. the..slo.t orgroove, being thus narrowerat' its central portionthan at its ends. Theenlargements at-the;ends are due to the fact that at the 'begimiiugtfthe operation the' cutter, owinggto the elasticity offthe 'severalfpartsoffthe machine and to. the unavoidable lost-:motion, in'the machine, has'a tendency to. creep: crosswise to; the direction of feed. At the endof the groove,

the cutter drops to the :same amount that g has crept at the beginning,since the'lifti'ng tendency or powerexe'rtedaou the cutter ceasesas soonas the feeding motion stops. The operation referred; to. above,producing a slot ofgreaterwidth (height) at the ends:

than at the central portion, isnot satisfac-p tory, since the resultdesired is the production of a slot or groove of uniform widthv (height)from end to end; in other words,v the lowerboundary of the; slot .orgroove should be as indicated by the solid 'lowerilin'e G. According tomy invention, the'cutterreceives a third'movement, whichis a to-andfromovement in a direction transeverse to the direction of feed indicatedbythearrjow: A, and. also transverse toi-the axis of rotation .6, ofthe, cutter G. In the particular;

embodiments illustrated, this .to-and-fro movement, inthe direction ofthe arrow H, is

imparted to the cutter G by the oscillation of; the arm 2 carrying theholder ,5,;or' .of the shaft 22; carrying the, holder24 (Fig. 5), or, bythe vreciprocation of the slide 29 carrying the holder 24 (Fig. 6).These to-and-frol movements; are made of such anfamplitude that thelower boundary of the slotor groove produced by the cutter willbeasindicatedat:.

G; in other words, such amplitude; is substantially equal tothe distancebetween the Obviously, I may provideother means ifor reciprocatingthewcutter and .for. effecting movement at right. angles to I the: feed,Nor. am limited to the machine illustratedfbut my invention may beapplied. to an ma-1' chines in which it is desird' to displ acejf cutteras described.

TI claim: Y f .1 1. In a milling machine, the combination of a cutterholder arranged; to be moved'relatively to' a work-piece inth'edirectiouof feed of a cutter, means for impartingTotation to saidholder, and means for imparting to said cutter holder,simultaneouslywith its feeding movement, a to-and-fro movementtransverse to the direction of feed and to the axis of rotation of thecutter.

2. In a milling machine, the combination of a cutter holder arranged tobe moved relatively to a work-piece in the direction of feed of acutter, means for imparting rotation to said holder, means for impartingto said cutter holder, simultaneously with its feeding movement, ato-and-fro movement transverse to the direction of feed and to the axisof rotation of the cutter, and means for varying the amplitude of suchto-and-fro movement.

3. In a milling machine, the combination of a frame, a rock arm pivotedon said frame, a cutter holder carried by said arm and adapted tobemoved relatively to a workpiece in the direction of feed of a cutter,and means for rocking said arm whereby, simultaneously with the feedingmovement of said holder, oscillatory movement is imparted to said holdertransversely to the direction of feed and to the axis of rotation of thecutter.

4. In a milling machine, the combination of a frame, an oscillatableelement carried by said frame, an eccentric bearing supported by saidelement, a cutter holder carried by said bearing and adapted to be movedrelatively to a work-piece in the direction of feed of a cutter, meansfor varying the position of said bearing with respect to said element,and means for imparting to said element, simultaneously with the feedingmovement of said holder, oscillation transversely to the direction offeed and to the axis of rotation of the cutter.

, 5. In a milling machine, the combination of a frame, a slide on saidframe, a cutter holder carried by said slide and adapted to be movedrelatively to a blank in the direction of feed of a cutter carried bysaid holder, and means for imparting to said slide, simultaneously withthe feeding movement of the holder, reciprocation transversely to thedirection of feed and to the axis of rotation of the cutter.

In testimony whereof, I have signed my name to this specification, this31st day of January, 1928.

OSW. FORST.

